Shims are used in many facets of assembly operations to position and fill gaps between assembled parts. The need for shimming is particularly acute in aerospace assembly operations due to the tight tolerance requirements and need to eliminate gaps at interfaces. Shims used for assembly operations generally fall within three categories. Solid shims are, in some cases, made of the same material as the interfacing parts. Laminated peelable shims may be made of foil layers that can be removed one-by-one until a good fit is achieved. Liquid shim materials may be useful in filling irregular or tapered interfaces. Liquid shim materials are typically used to fill gaps no bigger than 0.7 mm in width.